The present invention relates to a drill tube for use in upward rock drilling in which liquid is conducted through a drill string, in which the drill tube is a part, for driving a in-the-hole drilling machine and/or for flushing the drill hole.
When drilling long upwardly directed drill holes it is desirable to provide the drill tubes with a check valve so that the entire drill string is not emptied of water when further drill tubes are to be added to the drill string. A previously known solution, SE-B-456 269, has the drawback that the friction welded tube joints at the check valves give service life problems for the drill tubes.